1. Field of the Invention
The present invention relates to a pretreatment composition which is free of chromic acid; said composition is particularly useful as a final rinse in a metal pretreatment process.
2. Brief Description of the Prior Art
In the metal pretreatment process, it is known to employ a phosphating conversion coating which is usually followed by a final rinsing or sealing step. The rinsing composition usually comprises chromic acid. While effective in the rinsing step, chromic acid is, nonetheless, undesirable because of its toxicity and the attendant problems of disposal.
Hence, considerable work has been done in finding a replacement for chromic acid in the final rinsing step. The present invention provides a pretreatment composition which is essentially free of chromic acid.